1. Field of the Invention
Embodiments relate to a touch sensor.
2. Discussion of the Related Art
An input to a touch sensor may include a driving signal input through capacitance between a sensing electrode and a driving electrode of a touch panel and a noise signal input through capacitance between an object (e.g., a finger) touching the touch panel and a sensing node of the touch panel. A sensed signal may be an overlapped signal of the two signals.
A sensing unit of the touch sensor senses variation in mutual-capacitance of the touch panel and a digital processor of the touch sensor performs a digital signal processing of the sensed mutual-capacitance variation. When digital signal processed information is transmitted to a firmware, the firmware performs a calculation to extract x-y coordinate information and transmits the x-y coordinate information as final touch position information to a host. The resolution of information transmitted from the digital processor may be an index of accuracy of a coordinate calculation performed by the firmware.
In some cases, noise may be introduced to the signal detected by the touch sensor. For example, a fluorescent lamp located near the touch sensor or a charging device coupled to the touch sensor may cause interference with the output of an amplifier (for example, a calculation amplifier) included in an analog signal sensing unit of the touch sensor. This interference may cause the output to deviate from a normal operation range or overlap with noise, thus distorting the waveform of the output of the analog signal sensing unit. This distortion may prevent normal transmission of touch information.